Add `tracing` spans to light client chain scanning

This enables downstream users to profile how much time is spent in each
of the main subcomponents of the current chain scanner.

zcash_client_backend/CHANGELOG.md

@@ -6,6 +6,9 @@ and this library adheres to Rust's notion of
 [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+- `zcash_client_backend::data_api::chain::scan_cached_blocks` now generates
+  `tracing` spans, which can be used for profiling.
 
 ## [0.6.0] - 2022-11-12
 ### Added

zcash_client_backend/src/data_api/chain.rs

@@ -209,6 +209,7 @@ where
 ///
 /// Scanned blocks are required to be height-sequential. If a block is missing from the block
 /// source, an error will be returned with cause [`error::Cause::BlockHeightDiscontinuity`].
+#[tracing::instrument(skip(params, block_source, data_db))]
 #[allow(clippy::type_complexity)]
 pub fn scan_cached_blocks<ParamsT, DbT, BlockSourceT>(
     params: &ParamsT,

zcash_client_backend/src/welding_rig.rs

@@ -157,6 +157,7 @@ type TaggedBatch<P, S> = Batch<(AccountId, S), SaplingDomain<P>, CompactOutputDe
 type TaggedBatchRunner<P, S, T> =
     BatchRunner<(AccountId, S), SaplingDomain<P>, CompactOutputDescription, T>;
 
+#[tracing::instrument(skip_all, fields(height = block.height))]
 pub(crate) fn add_block_to_runner<P, S, T>(
     params: &P,
     block: CompactBlock,
@@ -189,6 +190,7 @@ pub(crate) fn add_block_to_runner<P, S, T>(
     }
 }
 
+#[tracing::instrument(skip_all, fields(height = block.height))]
 pub(crate) fn scan_block_with_runner<
     P: consensus::Parameters + Send + 'static,
     K: ScanningKey,

zcash_client_sqlite/CHANGELOG.md

@@ -6,6 +6,9 @@ and this library adheres to Rust's notion of
 [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+- `zcash_client_sqlite::DataConnStmtCache::advance_by_block` now generates a
+  `tracing` span, which can be used for profiling.
 
 ## [0.4.0] - 2022-11-12
 ### Added

zcash_client_sqlite/Cargo.toml

@@ -23,6 +23,9 @@ zcash_primitives = { version = "0.9", path = "../zcash_primitives" }
 bs58 = { version = "0.4", features = ["check"] }
 hdwallet = { version = "0.3.1", optional = true }
 
+# - Logging and metrics
+tracing = "0.1"
+
 # - Protobuf interfaces
 prost = "0.11"
 

zcash_client_sqlite/src/lib.rs

@@ -517,6 +517,7 @@ impl<'a, P: consensus::Parameters> WalletWrite for DataConnStmtCache<'a, P> {
         }
     }
 
+    #[tracing::instrument(skip_all, fields(height = u32::from(block.block_height)))]
     #[allow(clippy::type_complexity)]
     fn advance_by_block(
         &mut self,